The pearl harvest is where years of hard work and investing significant amounts of money finally pays off. The pearl harvest traditionally happens in the winter months, primarily because the nacre platelets become thinner as deposition decreases and the host mollusks’ metabolism begins to slow down. The reason that this matter is because the luster of the pearl is greater once harvested. The pearl may not grow as much in the winter, but the outer layers of the cultured pearls’ nacre do look better.

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When harvesting cultured pearls at a pearl farm, the nucleation period before harvest can be anywhere between eight months and six years. While freshwater pearls such as the Tahitian and South Sea pearls culture between two and six years, the Akoya pearls culture between eight months and two years.

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Once the pearls are brought onto shore from their mooring positions, the actual pearl harvest can begin. The pearls are opened by hand, one by one, and the pearl (or sometimes pearls) are extracted. With freshwater mussels and Akoya oysters, the meat and shell are used for another purpose or discarded. For Tahitian and South Sea oysters, the meat and shell are used along with the nucleation.

For those oysters, it is important to open the shell slightly, extract the pearl, and then another nucleus is inserted into the preformed pearl sac. That oyster goes into the sea to produce another pearl after going through a recovery period.

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After the harvest, it is important to make sure that any debris is removed from the pearl. They also make sure to polish the pearl to bring out a higher luster.

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After cleaning and polishing the pearls, they are going to be sorted by both size and quality categories. Many of the pearls are going to receive additional treatment, depending on the factory preparing the finished goods and the type of pearl that is harvested. It is possible that pearls are heat-treated, bleached, or pinked (this means soaking the pearl in red dye in order to bring out the pearl’s pink coloration.

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When harvesting pearls, a good harvest means that there are a large number of marketable pearls when compared to the number of nucleated oysters. The success of the overall harvest that year is dependent on the percentage of high-quality pearls. In an average harvest, only about half the pearls are marketable and less than 10 percent of those are considered ‘high quality’ pearls.

You may have read about pearl treatments before, you may have heard some of the negative connotations that people have when talking about these type of treatments. The truth is that all pearls are treated, you would not want a pearl that comes straight from the shell. Those pearls would not look the way that we have become accustomed to. In order to clear up some confusion, we are going to detail some of the pearl treatments, explain why these standard treatments are used, and tell you what you should be aware of.

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We are going to define pearl treatments as anything other than polishing the pearl. These pearl treatments alter the overall appearance of the pearl and may include working, cutting, drilling, waxing, filling, heating, bleaching, and irradiation.

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Again, once someone harvests these pearls, there is always some form of processing that occurs. Freshwater and Akoya pearls routinely receive some bleaching. All of the pearls that you see are polished and cleaned before they are put on sale. However, some treatments for cultured pearls are going to influence the aesthetic qualities of the pearl itself.

The high-quality cultured pearls are almost ready to go after they are polished and cleaned. However, a low-quality cultured pearl may still not have the desired luster. This means that the pearl farmer has a number of different options. They are able to sell the pearl at a heavy discount (meaning they make less money), peel the nacre off the pearl, and then try to sell it, or change the appearance of the pearl by applying a treatment. If the pearl does not have many other flaws, the treatment option is the most economically sensible and will be the common approach for a pearl farmer.

Most low-quality pearls undergo three main treatments. These include:

Luster treatment – A way to enhance the luster artificially. The pearl is first heated and then cooled again. Alternatively, it could mean a coating treatment on the pearl surface

Irradiation – This refers to using gamma rays to darken the nacre layers in freshwater pearls and the nucleus in Akoya pearls

Dyeing – The pearl farmer uses an organic dye such as silver nitrate to darken the pearl nacre using a coating as treatment. This practice is greatly frowned upon and not widely practiced. This is the equivalent of applying some clear nail polish on the pearl. Even though the luster is initially going to look fine, that artificial coat may eventually start to peel or chip away. This shows the low-luster pearl right underneath the surface. Even though unscrupulous pearl dealers have tried selling these to unsuspecting consumers before, it remains rare to see this happen.

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